Achieving stable interphases toward lithium metal batteries by a dilute and anion-rich electrolyte

It is necessary to find an ideal electrolyte suitable for high performance lithium metal batteries (LMBs). Herein, we construct a novel cluster-like and anion-rich dilute electrolyte system by using LiNO3 and trace lithium trifluoromethanesulfonate (LiOTf) in an ester-based electrolyte. In the designed system, NO3– is used as a modulator to regulate the coordination number of solvents and anions, and LiOTf is applied as a solubilizing agent of LiNO3 and trigger for the generation of large cluster. As a result, an anion-regulated solvation structure (ARSS) is obtained even in a dilute Li-ion concentration (<1.5 M), evidenced by various techniques, enabling the electrolyte a high ion-conductivity which vastly differs from a high concentration electrolyte system. Afterwards, the ARSS facilitates the formation of an inorganic-rich solid electrolyte interface (SEI) on both cathode and anode, ensuring the LMBs high stability and long cycling performance.